1. Field of the Invention
The present invention generally relates to semiconductor devices, and more particularly, to a stacked semiconductor device formed by stacking semiconductor elements.
2. Description of the Related Art
Recently, with the improvement in performance of semiconductor devices, stacked semiconductor devices formed by stacking multiple semiconductor elements have been widely used. In such stacked semiconductor devices, wire bonding is generally used as a wiring method of making interconnections between semiconductor elements.
FIG. 1 shows an exemplary structure of a stacked semiconductor device 100 in which interconnections are made by using wire bonding.
Referring to FIG. 1, a semiconductor element 101 is mounted on an interposer 111 via an insulating body 103, and a semiconductor element 102 is mounted on the semiconductor element 101 via an insulating body 104. The semiconductor element 101 includes, for example, an active element (not shown) and a passive element (not shown). A wiring connection portion 105, which is connected to the active element and the passive element, for example, is interconnected to a contact portion 109 of the interposer 111 by wire bonding with the use of a wire 107.
Similarly, the semiconductor element 102 includes an active element (not shown) and a passive element (not shown). A wiring connection portion 106, which is connected to the active element and the passive element, for example, is interconnected to a contact portion 109 of the interposer 111 by wire bonding with the use of a wire 108. The semiconductor elements 101 and 102 and the wires 107 and 108, for example, are fixed to the interposer 111 by a MOLD resin 110.
In the case of the stacked semiconductor device 100 using wire bonding as mentioned above, there is concern about problems due to variations caused in wire bonding process, such as differences in the loop shapes of wires, or variations in the resistance values of the wire connection portions and the connection portions of the wires.
Additionally, it is necessary to expose the wire connection portions on the semiconductor elements in order to make interconnections by wires. Hence, when stacking semiconductor elements, there is a limit in the size that an upper semiconductor element must be always smaller than a lower semiconductor element. Thus, there is a problem in that flexibility in designing is limited in the case of forming a stacked semiconductor device.